The present invention relates to an ultrasonic motor which is structured for applying an electric signal to an electrode provided on polarized piezoelectric elements to thereby cause a vibration wave on an ultrasonic stator fixed with the piezoelectric element, so that an ultrasonic rotor is driven while in pressure contact with the ultrasonic stator. More particularly, the invention is concerned with a structure of an ultrasonic motor lead board provided for applying an electric signal to piezoelectric elements of the ultrasonic motor.
Also, the invention relates to a method for manufacturing an ultrasonic motor including an ultrasonic motor lead board provided for applying an electric signal to piezoelectric elements.
Referring to FIG. 11 and FIG. 12, an ultrasonic motor of the related art includes an ultrasonic motor 910 provided with an ultrasonic stator 922, an ultrasonic motor support member 924, an ultrasonic motor shaft 932, an ultrasonic rotor 934 and an ultrasonic motor lead board 940.
The ultrasonic motor support member 924 has a through-hole 924a fixed with the ultrasonic motor shaft 932 by passing the ultrasonic motor shaft 932 through the through-hole 924a. The ultrasonic stator 922 has a center hole 922a, an ultrasonic stator main body 922b and projections (comb teeth) 922c for displacement magnification. The displacement-magnifying projections (comb teeth) 922c are provided in a surface of the ultrasonic stator main body 922b. A polarized piezoelectric element 950 is fixed on an underside of the ultrasonic stator main body 922b. The ultrasonic stator 922 is passed at its center hole 922a over the ultrasonic motor shaft 932 and firmly fixed to the ultrasonic motor shaft 932. The ultrasonic stator 922 is firmly fixed on the ultrasonic motor shaft 932 such that the center hole 922a has an end face at an outer peripheral portion thereof that is contacted with the ultrasonic motor shaft 932.
The ultrasonic motor lead board 940 is provided to apply an electric signal to an electrode provided on the piezoelectric element 950. The ultrasonic motor lead board 940 is arranged between the ultrasonic stator main body 922b and the ultrasonic motor support member 924. The ultrasonic motor lead board 940 is neither fixed to the ultrasonic stator main body 922b nor the ultrasonic motor support member 924. The ultrasonic motor lead board 940 has conductor patterns 940a, 940b having tips respectively soldered (respectively shown at 952a, 952b) to electrodes 950a, 950b of the piezoelectric element 950.
The ultrasonic rotor 934 includes an ultrasonic rotor lower member 934a, an ultrasonic rotor upper member 934b, a rotation member 934c, a set screw 934d and a spring contact member 934e. The ultrasonic rotor 934 is provided rotatable relative to the ultrasonic motor shaft 932 such that the lower member 934a at its underside contacts top surfaces of projections 922c of the ultrasonic stator 922.
A pressurizing spring 960 contacts with a summit of the spring contact member 934e. The elastic force of the pressurizing spring 960 puts the ultrasonic rotor 934 in pressure contact with the ultrasonic stator 922.
An ultrasonic motor drive circuit (not shown) generates an electric signal to drive the ultrasonic motor 910. The electric signal is input to the piezoelectric element 950 by way of the conductor patterns 940a and 940b on the ultrasonic motor lead board 940. Based on the electric signal, oscillation waves are produced on the ultrasonic stator 922 fixed with the piezoelectric element 950. Due to the oscillation wave, the ultrasonic rotor 934 rotates which is contacted in a pressurized state with the ultrasonic stator 922.
In the related art ultrasonic motor, however, the ultrasonic motor lead board is arranged between the ultrasonic stator and the ultrasonic motor support member but secured neither to the ultrasonic stator nor the ultrasonic motor support member. Meanwhile, a vertical gap exists between the ultrasonic motor lead board and the ultrasonic stator. Also, there is a vertical gap between the ultrasonic motor lead board and the ultrasonic motor support member.
As a consequence, the ultrasonic motor lead board might freely move in the vertical direction between the ultrasonic stator and the ultrasonic motor support member. As a result, there has been a concern that the conductor patterns on the ultrasonic motor lead board may be stripped off the ultrasonic motor lead board main body thus resulting in the occurrence of electric disconnection.
Furthermore, in the related art ultrasonic motor the ultrasonic stator has been secured onto the ultrasonic motor shaft in a state wherein the conductor patterns on the ultrasonic motor lead board are connected to the ultrasonic stator. Consequently, there has been difficulty in firmly fixing the ultrasonic stator to the ultrasonic motor shaft. Meanwhile, there has been a concern that in the fixing process the conductor patterns on the ultrasonic motor lead board may be stripped off the ultrasonic motor lead board main body thus resulting in the occurrence of electric disconnection.
It is therefore an object of the present invention to provide, in order to solve the above problems, an ultrasonic motor which is free from the concern that the conductor patterns on an ultrasonic motor lead board may be stripped off the ultrasonic motor lead board main body, and a method for manufacturing such an ultrasonic motor.
It is another object of the invention to provide an ultrasonic motor which is easy to assemble and manufacture.
In order to solve the above problems, the present invention is structured such that, in an ultrasonic motor having a structure in which an electric signal is applied to an electrode provided on a polarized piezoelectric element to cause a vibration wave on an ultrasonic stator fixed with the piezoelectric element, and an ultrasonic rotor is driven that contacts in a pressurized state with the ultrasonic stator, a combination is provided comprising: an ultrasonic motor shaft for supporting an ultrasonic stator and an ultrasonic motor support member; an ultrasonic motor support member firmly fixed on the ultrasonic motor shaft; an ultrasonic stator fixed with a piezoelectric element having an electrode and being polarization treated, and fixed on the ultrasonic motor shaft; an ultrasonic motor lead board having a conductor pattern firmly fixed to the ultrasonic motor support member; an ultrasonic rotor rotatably provided on the ultrasonic motor shaft and contacted with the ultrasonic stator; a pressurizing spring for pressurizing the ultrasonic stator and the ultrasonic rotor; wherein the conductor pattern of the ultrasonic motor lead board is electrically connected to the electrode of the piezoelectric element.
This structure can eliminate the concern that the conductor pattern of the ultrasonic motor lead board may be stripped off an ultrasonic motor lead board main body, or reduce this concern.
Also, it is preferred that the ultrasonic motor support member has a first through-hole to pass through the ultrasonic motor shaft and a second through-hole to pass through the conductor pattern of the ultrasonic motor lead board, the ultrasonic motor support member being firmly fixed on the ultrasonic motor shaft in such a state that the ultrasonic motor shaft is passed through the first through-hole of the ultrasonic motor support member, and the conductor pattern of the ultrasonic motor lead board, in a state passing through the second through-hole, being firmly fixed to the electrode of the piezoelectric element in the ultrasonic motor of the present invention.
Also, it is preferred that the ultrasonic stator has a cylindrical portion (122d) having a center hole, and that the ultrasonic stator is firmly fixed on the ultrasonic motor shaft in such a state that the cylindrical portion at one end face contacts the ultrasonic motor support member in the ultrasonic motor of the present invention.
Also, it is preferred that the ultrasonic motor lead board is firmly fixed to one surface of the ultrasonic motor support member, and that the ultrasonic stator is firmly fixed to the ultrasonic motor shaft in such a manner as to be contacted with the other surface of the ultrasonic motor support member in the ultrasonic motor of the present invention.
This structure can eliminate the concern that the conductor pattern of the ultrasonic motor lead board may be stripped off an ultrasonic motor lead board main body, or can reduce this concern.
Also, the ultrasonic motor of the invention is easy to assemble and manufacture.
Furthermore, in an ultrasonic motor manufacturing method for manufacturing an ultrasonic motor that is structured to apply an electric signal to an electrode provided on a polarized piezoelectric element to cause a vibration wave on an ultrasonic stator fixed with the piezoelectric element, and an ultrasonic rotor is driven that contacts in a pressurized state with the ultrasonic stator, the present invention is provided such that the ultrasonic motor has an ultrasonic motor support member with a first through-hole to pass through an ultrasonic motor shaft and a second through-hole to pass through a conductor pattern of an ultrasonic motor lead board. Next, the ultrasonic motor support member is firmly fixed on the ultrasonic motor shaft in a state such that the ultrasonic motor shaft is passed through the first through-hole of the ultrasonic motor support member. Next, the ultrasonic stator (122) is firmly fixed on the ultrasonic motor shaft (132). Next, the ultrasonic motor lead board having the conductor pattern is firmly fixed to the ultrasonic motor support member. Next, the conductor pattern of the ultrasonic motor lead board is firmly fixed to the electrode of the piezoelectric element such that the conductor pattern of the ultrasonic motor lead board is passed through the second through-hole. Next, an ultrasonic rotor is arranged rotatable relative to the ultrasonic motor shaft and is contacted with the ultrasonic stator. Next, the ultrasonic stator and the ultrasonic rotor are put in pressure contact.
This structure can eliminate the concern that the conductor pattern of the ultrasonic motor lead board may be stripped off an ultrasonic motor lead board main body, or may reduce this concern.
Also, the use of the ultrasonic motor manufacturing method of the present invention makes an ultrasonic motor easy to assemble and manufacture.
Furthermore, in an ultrasonic motor manufacturing method for manufacturing an ultrasonic motor that is structured to apply an electric signal to an electrode provided on a polarized piezoelectric element to cause a vibration wave on an ultrasonic stator fixed with the piezoelectric element, and an ultrasonic rotor is driven that contacts in a pressurized state with the ultrasonic stator, the present invention is provided such than an ultrasonic motor support member is provided with a first through-hole to pass through an ultrasonic motor shaft and a second through-hole to pass through a conductor pattern of an ultrasonic motor lead board. Next, the ultrasonic motor lead board having the conductor pattern is firmly fixed to the ultrasonic motor support member. Next, the ultrasonic motor support member is firmly fixed on the ultrasonic motor shaft such that the ultrasonic motor shaft is passed through the first through-hole of the ultrasonic motor support member. Next, the ultrasonic stator is firmly fixed on the ultrasonic motor shaft. Next, the conductor pattern of the ultrasonic motor lead board is firmly fixed to the electrode of the piezoelectric element such that the conductor pattern of the ultrasonic motor lead board firmly fixed to the ultrasonic motor support member is passed through the second through-hole. Next, an ultrasonic rotor is arranged rotatable relative to the ultrasonic motor shaft and contacted with the ultrasonic stator. Next, a pressurizing spring is arranged such that the ultrasonic stator and the ultrasonic rotor are put in pressure contact.
This structure can reduce the concern that the conductor pattern of the ultrasonic motor lead board may be stripped off an ultrasonic motor lead board main body.
Also, the use of the ultrasonic motor manufacturing method of the present invention makes an ultrasonic motor easy to assemble and manufacture.